1. Field of the Invention
The present invention relates generally to a coffee brewing system which utilizes an insulated carafe to receive brewed coffee and automatically turns itself off under appropriate conditions.
2. Description of the Prior Art
In the past, coffee brewing systems intended for domestic use have customarily been equipped with uninsulated receptacles to receive the brewed coffee. These systems typically provide a heater plate on which the receptacle is supported after completion of the brew cycle. The purpose of the heater plate is to keep the coffee warm until it is completely consumed or discarded. However, such an arrangement is costly in that it requires the continued expenditure of power. It also heats the environment which is doubly costly when the room in which the system is located is air conditioned. Such continued heating of coffee also detracts from its flavor when the time period is an extended one. Additionally, drippage of coffee is often known to occur onto the heater plate. This causes burning of the coffee on the heater plate, customarily leaving an unpleasant hardened residue which can subsequently become transferred to the receptacle. Eventually, it becomes necessary to clean the surfaces of both the heater plate and the bottom of the receptacle.
Devices have previously been known for automatically turning off appliances at some desired time. One such invention is disclosed in U.S. Pat. No. 4,480,173 to Butterfield which describes a water heater in the nature of a pressure cooker. In the instance of that patent, a water level transducer controls a motorized inlet valve to close the valve when the water level in the tank reaches a predetermined level and opens the valve when the water falls below that level. However, the Butterfield patent does not disclose a coffee brewing system and is not concerned with turning the heater off a predetermined time after a brew cycle intended to yield a predetermined amount of coffee has been accomplished. More directly concerned with coffee brewing processes are the U.S. Pat. Nos. 3,869,968 to Ihlenfeld and 3,759,161 to Anderson. In each instance, the patent discloses a cfffee brewer of a conventional type which utilizes a heater plate to maintain the temperature of the brewed coffee in the coffee pot after completion of a brew cycle. In each instance, provision is made for deenergizing the heater mechanism used in the brewing operation, while continuing to energize the auxiliary heater mechanism used to maintain the temperature of the brewed coffee.